If I am about to retire, can I get my new PCS orders changed to my last duty station where I left my family?

No you can't change your orders because you plan to retire. If you had 19.5 years at the point you were notified you could retire in lieu of PCS. You'll have to comply with the assignment instructions and either move your family or not.

One thing you might want to try is to ask your branch manager if they'd be willing to cancel your orders and FSTE you long enough to retire in place. It's almost impossible these days to get your orders switched with the enlisted Marketplace. Once your assignment is generated it is out of the hands of your branch manager. But, the branch chief might be capable of supporting you staying in place for one more year and deleting your current assignment. You would still be away from your family, but you wouldn't have to move them or come out of pocket for a second residence

Apply for a hardship.

So I had the same situation with a twist, I was in Honduras with a follow-on assignment choice, family in Alaska, and 7 months left after Honduras required to retire. I could go back to AK but would have to do 3 years and was unable to retire in Honduras. So I selected a location-based upon retirement services, Ft. Campbell. Couple of thoughts here. Have you talked to branch? Do you not get an assignment of choice after a hardship tour? Why are you waiting to drop your packet? If I were you, I would drop the packet now so you can come into your next unit with a "My whole focus is retirement and preparation" mindset and message to your gaining unit. THEY NEED TO KNOW! Branch will take you more seriously as well, your next unit may not want you in that slot after you drop that packet. It takes a full year to make a good transition, I am telling you this as one who just did it successfully. There are so many programs that are out there and you are about to be swimming in transition info that will make your head spin when you fully grasp what you are about to do! I knew several people who left their family in place to stay where they wanted to retire, where their house was, knowing it would be one year, minus leave, and they would be doing a fellowship at a company like Amazon. So, that being said, you may want to focus on your retirement packet at the moment, try to contact branch, try to contact your gaining unit and let them know you are about to retire, as they may say no thanks. Finally, you need to do some research to plan your transition, look into programs. Check out these links
https://www.hireheroesusa.org/
https://hireourheroes.org/veterans/find-a-mentor.html
https://ivmf.syracuse.edu/
https://vets2pm.com/veterans/
https://www.acp-usa.org/

Feel free to contact me if you have any questions as well.

All you can do is have that base on your ASK list and put in a 4187 requesting it (might have changed since I retired in '13)

Under the new evaluation system, they have done away from the RCP meaning you can stay in until age 60, with that in mind, HRC will not know if your going to drop your packet. You might can email your branch mwr and maybe get some feed back or your branch sym. Sometime they do use some common sense. Good luck